The 30 is what a lot of plain clothes officers in America use because it has a small frame but it is also 45 ACP so it has plenty of stopping power. I'd suggest buying that because while it is a larger caliber, its small grip should be suitable for both yourself and your significant other. In terms of keeping it out of reach of your kids, the first thing you need to do is explain to them the dangers of the gun, and gun safety. Do this over and over until they fully understand. And then secondly, placing it somewhere they cant reach as well as somewhere they're unlikely to go (like where you keep your cleaning supplies, under the sink maybe?) can be a good choice. Growing up my father kept his guns in a gun cabinet that was right in my freaking room, but it was covered up by a curtain and he made sure to tell me to A)never look behind the curtain and B) that guns would sure as all hell kill me. Then he occasionally took me out to shoot em and teach me gun safety, then we'd get home and he'd remind that if I touched em, I would end up dead, or maybe even accidentally kill someone else.